Composite superconductor and method of the production thereof

ABSTRACT

A composite superconducting wire using ceramic superconductor material in which one or more elongated superconductor material are accomodated in one or more grooves formed on an elongated reinforcing member so that a long size superconductor wire can be provided. Various methods of producing such composite superconductor wire are also disclosed.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to a composite superconductor and moreparticularly to a composite superconducting wire using ceramicsuperconductor material and the method of the production thereof.

2. DESCRIPTION OF THE PRIOR ART

As the superconductor material, metal superconductor, ceramicsuperconductor and organic superconductor are known.

It has been proposed to manufacture long superconductor wires and/orcoils using superconductor material. Recently there have been foundceramic superconductors of high critical temperature and it has beendiscussed to manufacture superconductor wires and coils using theceramic superconductor material.

Since the ceramic superconductor material is very brittle and treatmentthereof is difficult, it has been considered difficult for those skilledin the art to manufacture ceramic superconductor long wires and coils.In order to solve the difficulty mentioned above, there has been aproposal that in view of the fact that the ceramic superconductor can beproduced by sintering ceramic superconductor powder, the ceramicsuperconductor powder is filled in a metallic sheath, which is drawn orspun so as to provide an elongated superconductor wire with a desireddiameter then the wire is subjected to a thermal process with atemperature higher than 990° C. for a few hours.

However, even if the ceramic superconductor covered by the metallicsheath is subjected to the thermal process, there occurs a shortage ofelements such as oxygen for realizing the desired superconductorproperty and therefore, there occurs such a problem that the desiredsuperconductivity can not be obtained.

If sufficient oxygen is supplied to the process, since the ceramicsuperconductor may be shrunk by the thermal processing, it is stilldifficult to manufacture long ceramic superconductor wires. Similarly,there is a problem of difficulty of manufacturing ceramic superconductorcoils.

SUMMARY OF THE INVENTION

Before the description proceeds, it is to be noted that since thearrangement of the superconductor wire according to the presentinvention is made of an elongated reinforcement and one or moreelongated ceramic superconducting members accommodated in one or moregrooves defined in the reinforcing member, the term "elongatedsuperconducting material" means the ceramic superconducting member to beaccommodated or already accommodated in the groove or grooves and theterm "composite superconducting wire" means the product of thesuperconducting wire according to the present invention.

An essential object of the present invention is to provide a compositesuperconducting wire using ceramic superconductor having a sufficientlong size and a desired superconductor property.

Another object of the present invention is to provide a method of theproduction of the composite superconducting wire of a long size with adesired superconductor property.

According to the present invention, there is provided a compositeceramic superconducting wire made of an elongated reinforcing member andone or more ceramic elongated superconductor material accommodated in agroove or grooves defined on the elongated reinforcing member so as toextend generally in the longitudinal direction of the elongatedreinforcing member.

The groove may be formed on the outer surface portion of the reinforcingmember to extend linearly in the longitudinal direction of the elongatedreinforcing member.

The groove may be formed in a spiral shape extending along thecylindrical surface of the reinforcing member.

The number of the groove is not limited to one but a plurality ofgrooves may be formed on the reinforcing member.

The ceramic elongated superconductor material may have the structuredefined by the following equation.

    Aa Bb Cc                                                   (1)

wherein A denotes at least one kind of the element selected from the IAgroup, IIA group, IIIA group of the periodic table, B denotes at leastone kind of the element selected from the IB group, IIB group and IIIAgroup of the periodic table, and C denotes at least one kind of elementselected from a group consisting of oxygen, fluorine, nitrogen, carbonand sulfur.

Examples of the IA group elements are Li, Na, K, Rb, Cs and Fr, andexamples of the Ib group elements are Cu, Ag and Au.

Examples of the IIA group elements are Be, Mg, Ca, Sr, Ba and Ra, andexamples of the IIb group elements are Zn, Cd and the like.

Examples of the IIIA group elements are Sc, Y and lanlhomides (e.g. La,Ce, Gd and Lu) and actinides (e.g. Ac Th, Pa and Cf), and examples ofIIIA group elements are Al, Ga, In and Tl.

Among the above exemplified elements, those selected from the IB groupelements, the IIA group elements, the IIIB group elements, and oxygenare preferred. Among the IB group elements, Cu and Ag are morepreferred, particularly, Cu is most preferred.

As the examples of material of the reinforcing member, there may be usedvarious kinds of material which are not reacted at the time of thethermal processing of the ceramic superconductor material and have agood thermal resistance at the thermal processing temperature. Examplesof the material of the reinforcing member are stainless steel, Ag andthe composite material of the stainless steel and Ag.

In the composite superconducting wire according to the presentinvention, since one or more grooves are defined on the peripheralportion of the elongated reinforcing member so as to extend in thelongitudinal direction of the elongated reinforcing member and theelongated superconductor material is accommodated in the groove, theceramic composite superconducting wire according to the presentinvention is easy to treat and can be manufactured as a very longsuperconducting wire even if the elongated superconductor materialitself is brittle and hard to treat.

In addition, even if the ceramic superconductor material is shrunkduring the sintering process, since the elongated superconductormaterial can be accommodated in the groove of the reinforcing member,the ceramic composite superconducting wire can be manufactured in a verylong wire.

According to the present invention, there is provided method of theproduction of the ceramic composite superconducting wire.

In the first method, one or more elongated superconductor materials areaccommodated in one or more grooves, each groove being formed on anelongated reinforcing member so as to extend in a longitudinal directionof the reinforcing member. Subsequently, the reinforcing member iscovered with an outer pipe. Then the reinforcing member with the ceramicelongated superconductor material is subjected to a wire drawing processand the outer pipe is removed, thereby to obtain a superconducting wire,which is in turn subjected to a thermal treatment, whereby a ceramiccomposite superconducting wire can be obtained.

According to the first method, the ceramic elongated superconductormaterials are accommodated in each groove, whereby the ceramic elongatedsuperconductor materials can be made integral with the reinforcingmember. By covering the reinforcing member with the ceramic elongatedsuperconductor material by pipe, the elongated superconductor materialand the reinforcing member can be tightly integrated. By drawing thereinforcing member covered by the pipe with the ceramic elongatedsuperconductor material in the groove, a superconducting wire with adesired diameter can be obtained. Thereafter the pipe is removed and thesuperconducting wire is subjected to the thermal treatment for sinteringunder supply of suitable element or elements in order to obtain adesired superconductor property. By the sintering process, the ceramicsuperconductor material can be tightly integrated.

In the second method, one or more elongated ceramic superconductormaterials are accommodated in the groove formed on an elongatedreinforcing member for extending in s longitudinal direction.Subsequently, the reinforcing member is covered with an outer pipe. Thenthe reinforcing member with the ceramic superconductor material issubjected to a wire drawing process followed by a twisting process, thenthe outer pipe is removed to obtain a superconducting wire assemblywhich is in turn subjected to a thermal treatment, whereby a compositesuperconducting wire can be produced.

According to the second method, the ceramic elongated superconductormaterials are accommodated in each groove, whereby the elongatedsuperconductor materials can be made integral with the reinforcingmember. By covering the reinforcing member with the elongatedsuperconductor material with the pipe, the elongated superconductormaterial and the reinforcing member can be tightly integrated. Bydrawing the reinforcing member covered by the pipe with the elongatedsuperconductor material in the groove, a superconductor wire with adesired diameter can be obtained. Thereafter the pipe is removed and thesuperconductor wire assembly is subjected to the thermal treatment forsintering under supply of suitable element or elements in order toobtain a desired superconductor property. By the sintering process, theelongated superconductor material can be tightly installed in the innerportion of the groove of the reinforcing member in a pressed manner.

In addition, by the twisting process, the reinforcing member and theelongated superconductor material are shaped in a spiral shape, wherebythe superconductor wire with the elongated superconductor material isformed in the spiral shape so that the length of the compositesuperconducting wire can be increased.

In the third method, elongated superconductor materials are accommodatedin a groove formed on an elongated reinforcing member for extending in slongitudinal direction. Subsequently, the reinforcing member is coveredwith an outer pipe. Then the reinforcing member with the elongatedsuperconductor material is subjected to a wire drawing process followedby a process of coiling the reinforcing member with the ceramicelongated superconductor material in a coil shape (referred to as acoiling process), and the outer pipe is removed to obtain asuperconductor wire assembly, which is in turned subjected to a thermaltreatment, whereby a composite superconducting wire can be produced.

According to the third method, the elongated superconductor materialsare accommodated in each groove, whereby the elongated superconductormaterials can be made integral with the reinforcing member. By coveringthe reinforcing member and elongated superconductor materials with thepipe, the elongated superconductor material and the reinforcing membercan be tightly integrated in the bottom of the groove of the reinforcingmember. By drawing the reinforcing member covered by the pipe with theelongated superconductor material in the groove, a superconductor wireassembly with a desired diameter can be obtained. Thereafter the pipe isremoved and the superconductor wire assembly is subjected to the thermaltreatment for sintering under supply of suitable element or elements inorder to produce a composite superconducting wire with a desiredsuperconductor property. By the sintering process, the elongatedsuperconductor material can be tightly integrated in the inner portionof the groove of the reinforcing member.

In the fourth method, elongated superconductor materials areaccommodated in a groove formed on an elongated reinforcing member forextending in a longitudinal direction. Subsequently, the reinforcingmember is covered with an outer pipe. Then the reinforcing member withthe elongated superconductor materials is subjected to a wire drawingprocess followed by the twisting process and coiling process, and theouter pipe is removed to obtain a superconductor wire assembly, which isin turn subjected to a thermal treatment.

The material of the ceramic superconductor may be produced in such amanner that suitable raw material of the ceramic superconductor ispreliminarily sintered and the sintered substance is broken into ceramicsuperconductor powder and the ceramic superconductor powder isaccommodated in a suitable sheath to obtain a wire shape.

As the elongated superconductor material, there may be used a bundle ofa plurality of ceramic superconductor filaments or twisted ceramicsuperconductor filaments. In this case, the filaments and/or the bundleof the filaments may be coated by a suitable coating material. Suchcoating material may be removed at the pipe removing process. As theexamples of the coating material, there may be used Cu, Al, Ag. As theexamples of the solvent for removing the pipe, any solvent may beselected corresponding to the material of the pipe, and there may beused nitric acid and sulfric acid.

The number and shape of the grooves for accommodating the elongatedsuperconductor material may be decided as desired.

In case the groove for accommodating the elongated superconductormaterial is shaped in a spiral shape, it is possible to manufacture acoil of the superconductor wire and in case the groove is formed on theperipheral surface of the reinforcing member, the elongatedsuperconductor material accommodated in the groove is pressed to thebottom of the groove due to shrinkage of the superconductor when thesuperconductor is sintered, whereby the elongated superconductormaterial can be held in the groove tightly.

In case a plurality of grooves are formed on the peripheral surface ofthe reinforcing member, the same technical effects as mentioned abovecan be attended.

In case the ceramic superconductor is formed by the material defined bythe equation (1), the same effects may be attended.

In order to obtain the effects mentioned above, the reinforcing membermay be formed by various kind of material so far as the material is notreacted at the time of thermal processing of the ceramic superconductorwire assembly and has an enough thermal resistivity for the thermaltreating temperature.

In a further method, one or more elongated superconductor materials areaccommodated in one or more grooves, each groove being formed on anelongated reinforcing member so as to extend in s longitudinal directionof the reinforcing member. Subsequently, the reinforcing member iscovered with an outer pipe. Then the reinforcing member with the ceramicelongated superconductor material is subjected to a wire drawingprocess, thereby to obtain a superconducting wire covered with the outerpipe, which is in turn subjected to a thermal treatment, whereby aceramic composite superconducting wire covered with the outer pipe canbe obtained.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of a superconductor wireaccording to the present invention,

FIG. 2 is a cross sectional view of the superconductor wire shown inFIG. 1,

FIG. 3 is a schematic diagram showing a process of a method of theproduction of the superconductor wire shown in FIG. 1,

FIG. 4 is a perspective view showing another example of thesuperconductor wire according to the present invention, wherein theceramic superconductor is fitted in a spiral groove,

FIG. 5 is a cross section view showing a further example of thesuperconductor wire according to the present invention, wherein theceramic superconductors are filled in four grooves,

FIG. 6 is a perspective view showing a still further example of thecoiled superconductor wire according to the present invention,

FIG. 7 is a cross sectional view showing a still further example of thesuperconductor wire according to the present invention,

FIG. 8 is a perspective view showing a still further example of thesuperconductor wire according to the present invention,

FIG. 9 is a cross sectional view of the superconductor wire shown inFIG. 8,

FIG. 10 is a schematic view showing a process of the production of thesuperconductor wire shown in FIG. 8,

FIG. 11 is a perspective view showing a still further example of thesuperconductor wire according to the present invention; wherein aplurality of ceramic superconductor filaments are fitted in the groove,

FIG. 12 is a cross sectional view of the superconductor wire shown inFIG. 11,

FIG. 13 is a perspective view shown a still further example of thesuperconductor wire according to the present invention, wherein thesuperconductor filaments are fitted in the spiral groove,

FIG. 14 is a cross sectional view showing a still further example of thesuperconductor wire according to the present invention, wherein thesuperconductor filaments are fitted in four grooves,

FIG. 15 is a perspective view showing a still further example of thesuperconductor wire according to the present invention, wherein thesuperconductor wire shown in FIG. 13 is formed in a coil,

FIG. 16 is a perspective view showing a still further example of thesuperconductor wire according to the present invention, wherein thesuperconductor wire is accommodated in an outer enclosure,

FIG. 17 is a cross sectional view showing the superconductor wire shownin FIG. 16,

FIG. 18 is a perspective view showing a still further example of thesuperconductor wire according to the present invention, wherein thespiral superconductor wire is accommodated in an outer enclosure,

FIGS. 19 and 20 are cross sectional view showing a still further exampleof the superconductor wire according to the present invention whereinthe superconductor wire is accommodated in an outer enclosure,

FIG. 21 is a perspective view showing a coil of the superconductor wireaccording to the present invention, wherein the superconductor wire isaccommodated in an outer enclosure,

FIG. 22 is a schematic view showing an example of an apparatus forfitting the superconductor in the groove,

FIGS. 23 to 30 are respectively schematic diagrams showing variousexamples of the process of the production of the superconductor wireaccording to the present invention,

FIGS. 31 to 33 are cross sectional view showing various examples of thesuperconductor wire covered with an outer pipe,

FIG. 34 is a perspective view showing a further example of thesuperconductor wire according to the present invention,

FIGS. 35 to 37 are respectively show examples of the methods of theproduction of the superconductor wires according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 showing an example of the composite superconductingwire 10 according to the present invention, there is shown an elongatedreinforcing member 1 made of stainless steel having a round shape in asectional shape. An elongated groove 2 having a generally circular shapeis defined on the cylindrical surface portion of the reinforcing member1 so as to extend straight in a longitudinal direction of thereinforcing member 1. Elongated superconductor material 3 made ofceramic superconductor substance of Y₁ Ba₂ Cu₃ O_(7-x) is accommodatedin the groove 2 of the reinforcing member 1. In the compositesuperconducting wire shown in FIG. 1, since the brittle elongatedsuperconductor material 3 is accommodated in the groove 2, namely theelongated superconductor material 3 is covered by the reinforcing member1, it becomes possible for a man to touch the ceramic compositesuperconductor wire 10 and to bend it without any deterioration of thesuperconductor property. It is also possible to manufacture a longsuperconductor wire by making the reinforcing member long.

FIG. 3 shows a process of making the composite ceramic superconductorwire 10 of the present invention, wherein an elongated superconductormaterial 3a covered with Cu layer 3b and a basic material is of thereinforcing member 1 with the groove 2 are prepared in the step A. Theelongated superconductor material 3a is accommodated in the groove 2 inthe step B and in turn the reinforcing member 1 with the elongatedsuperconductor material 3a is covered by a Cu pipe 5 in the step C. Thenthe entire body is subjected to a wire drawing process in the step D sothat the superconductor wire assembly is drawn and extended to the wirehaving a desired outer diameter. Then the Cu pipe 5 and Cu layer 3b areremoved by a chemical treatment in the step E, and the ceramicsuperconductor wire assembly is subjected to a thermal process in thestep F with a temperature higher than 900° C. for at least a severalhours, whereby the composite superconducting wire shown in FIGS. 1 and 2mentioned above can be obtained.

As the ceramic superconductor basic material, there may be used simplesubstance or compound thereof so far as the substance contains materialand/or materials which show superconductor property.

In performing the thermal treatment, there occurs shrinkage of theelongated superconductor material and there could be formed a gapbetween the elongated superconductor material 3a and the reinforcingmember 1 and therefore, O₂ can be sufficiently supplied to the gap, sothat a good superconductor property could be obtained. Specifically, thecritical temperature of the superconductor wire was 91° K.

In the example mentioned above, in place of using the Cu pipe, Al or Agpipe may be used.

In the process of removing the Cu pipe mentioned above, a part 3x of theCu pipe covering the elongated superconductor material 3a at the bottomof the groove 2 may not be removed but the upper half portion of the Cupipe is removed as shown in FIG. 7.

FIG. 4 shows another embodiment of the composite superconductor wire ofthe present invention, wherein the groove 2 is formed in a spiral manneron the cylindrical surface of the reinforcing member 1.

In the embodiment shown in FIG. 4, similar to the embodiment shown inFIGS. 1 and 2, it becomes possible to handle the compositesuperconducting wire 10 by man's hand and it is also possible tomanufacture the composite superconducting wire of long size.

Moreover, the length of the composite superconducting wire can beincreased easily relative to the embodiment shown in FIG. 1 by makingthe elongated superconductor material 3 to extend in a spiral shapearound the cylindrical surface of the reinforcing member 1. Moreover, incase the elongated superconductor material 3 is shrunk in the spiralgroove 2, the elongated superconductor material 3 is pressed to thebottom of the groove 2 so that the elongated superconductor material 3can be tightly integrated with the reinforcing member 1.

With respect to the process for manufacturing the compositesuperconducting wire shown in FIG. 4, even when the reinforcing memberwith the straight groove is used, it is sufficient to add a twistingprocess between the wire drawing process and cover removing process, sothat it is possible to make the manufacturing process as simple aspossible.

FIG. 5 shows a further example of the composite superconducting wire ofthe present invention, wherein four grooves 2 are formed in thereinforcing member 1. The grooves 2 are respectively separated by thesame angular distance. The elongated ceramic superconductor wires 3 areaccommodated in the respective grooves 2. In the compositesuperconducting wire shown in FIG. 5, the various advantages mentionedabove can be attended. In addition, the number of the grooves 2 that isthe number of the elongated superconductor material may be increased upto about 15 or 16.

FIG. 6 shows a further example of the composite superconducting wire ofthe present invention, wherein the reinforcing member 1 is formed in aspiral shape. In the example shown in FIG. 6, a coil having a desirednumber of turn can be manufactured easily.

As to the manufacturing process, the composite superconducting wireshown in FIG. 6 can be manufactured by only adding a process of twistingthe reinforcing member 1 between the drawing process and cover removingprocess so that the grooves are shaped in a spiral shape. However, thespiral shaping may be made after the superconducting wire assembly iscompleted.

In a further example of the composite superconducting wire, there may beadded a stabilizing conductor 4 made of Cu so as to extend in thecentral portion of the reinforcing member 1 as shown in FIGS. 8 to 10.In the embodiment, since the stabilized conductor 4 is laid in thereinforcing member 1, in case the elongated superconductor material 3 isformed to the normal conductive condition, the current mainly flowsthrough the stabilizing conductor 4, whereby it is possible to preventthe superconductor wire from being burned out.

FIG. 10 shows the respective processes for manufacturing the compositesuperconducting wire shown in FIG. 8 which is similar to those shown inFIG. 3 except that the stabilizing member 4 is situated in thereinforcing member 1.

In a further example of the composite superconducting wire, as theelongated superconductor material, a plurality of superconductorfilaments (generally shown in the reference numeral 3) which are twistedmay be used as shown in FIGS. 11 to 14. The twisted superconductorfilaments may be obtained in such a manner that after a plurality ofsuperconductor filaments are formed using the ceramic superconductorbasic material, the superconductor filaments are twisted and subjectedto a heat treatment with a temperature higher than 900° C.

The manufacturing process of the composite superconducting wire shown inFIG. 11 is similar to that shown in FIG. 3 except that the twistedsuperconductor filaments are accommodated in the groove 2.

In the example shown in FIGS. 11 to 14, since the superconductorfilaments are twisted, distortion of the filaments due to shrinkage atthe time of sintering process can be effectively eliminated.

FIG. 15 shows a coiled composite superconducting wire using the twistedsuperconductor filaments mentioned above.

FIGS. 16 and 17 shows a still further example of the compositesuperconducting wire. The composite superconducting wire 10 composed ofthe reinforcing member 1 and the elongated superconductor material 3accommodated in the groove 2 shown in FIG. 1 is accommodated in an outerenclosure 11 made of stainless steel with a generally rectangular shapeas shown, so that there is provided a space 12 for flowing the coolingmedium around the composite superconducting wire 10.

In the example shown in FIGS. 16 and 17, liquid nitrogen is passedthrough the space 12 surrounded by the outer enclosure 11 along thecomposite superconducting wire 10 so that since the temperature of theliquid nitrogen is lower than the critical temperature of the ceramicsuperconductor wire, the composite superconducting wire 10 can be keptlower than its critical temperature.

In the example shown in FIGS. 16 and 17, the composite superconductingwire 10 may be produced in the same process shown in FIG. 3. After thecomposite superconducting wire 10 is produced, four flat sheets formaking the outer enclosure 11 is supplied continuously and the sheet iswelded, so that there can be produced the outer enclosure 11 having asize larger than the diameter of the reinforcing member 1 for flowingthe cooling medium. The shape of the enclosure 11 is not limited to therectangular shape but may be selected round shape as desired. When theflat sheets are welded, the rectangular enclosure 11 may be produced,when arcuated sheets are welded, a round enclosure or elipticalenclosure may be produced.

FIG. 18 shows a still further example of the composite superconductingwire of the spiral shape which is accommodated in the outer enclosure11. The composite superconducting wire per se is the same as that shownin FIG. 4. Similarly in the example shown in FIG. 19, the compositesuperconducting wire shown in FIG. 5 in which a plurality of theelongated superconductor materials 3 are accommodated respectively inthe grooves 2 of the reinforcing member 1 is accommodated in the outerenclosure 11. In the example shown in FIG. 21 the superconductor wireshown in FIG. 12 in which the twisted superconductor filaments 3 areaccommodated in the groove 2 of the reinforcing member 1 is accommodatedin the outer enclosure 11. In the example shown in FIG. 20, the surfacearea of the composite superconducting wire to be contacted with theliquid nitrogen can be increased and therefore, cooling effect of thecomposite superconducting wire can be increased. FIG. 21 shows anexample of a coiled composite superconducting wire using the variousexamples of the composite superconducting wire shown in FIGS. 16 to 20.

FIG. 22 shows an essential structure of an apparatus for fitting in theelongated superconductor material 3 in the spiral groove 2 of thereinforcing member 1 in order to manufacture the compositesuperconducting wire as shown in FIG. 4 in which the elongatedsuperconductor material 3 is fitting in the spiral groove 2. A pair ofwire guiding plates 6 and a collecting die 7 are disposed at respectivepositions. The elongated superconductor material 3 is supplied to thewire collecting die 7 through the wire guiding plates 6, when thereinforcing member 1 is rotated around the longitudinal axis thereof andadvanced in the direction shown by the arrow mark. Since the elongatedsuperconductor material 3 has a suitable flexibility, the elongatedsuperconductor material 3 can be fitted in the groove 2. In case theelongated superconductor material is covered by Cu pipe 3b, the processto fit the elongated superconductor material 3 in the groove 2 can bemade more easily.

The elongated superconductor material 3 having a suitable flexibilitymay be produced by mixing the alcoholic solvent in the superconductormaterial, then the superconductor material is spun in the wire shape bythe Doctor brade method (slip casting method). In this case, since theelongated superconductor material has a sufficient flexibility, theelongated superconductor material can fit in the groove 2 without Cupipe. The alcoholic solvent is volatilized when the wires are subjectedto the thermal process, and the superconductor property is not harmed bythe alcoholic solvent.

The groove 2 of the reinforcing member 1 may be formed by a cuttingprocess.

There may be obtained a long size composite superconducting wire byconnecting the respective Cu pipes 5 of the respective compositesuperconducting wires in series being TIG welding, MIG welding method orhigh frequency welding method.

In order to provide the composite superconducting wire as shown in FIG.4 in which the elongated superconducting material 3 is accommodated inthe spiral shape groove, the reinforcing member having the groove 2extending straightly in place of using the spiral groove.

FIG. 23 shows an example of the second method of the production of thecomposite superconducting wire as shown in FIG. 4 using the reinforcingmember having a straight groove. In the method shown in FIG. 23, themethod is similar to the method shown in FIG. 3 except that a twistingprocess (step (E) in FIG. 23) is added between the wire drawing step(step D in FIG. 23) and Cu pipe removing step (step F in FIG. 23).

In the example shown in FIG. 23, the drawn superconductor wire assemblyis twisted around the longitudinal axis of the superconductor wire 10 sothat the groove 2 and the elongated superconductor material 3 is shapedin the spiral shape as shown in FIG. 4. The twisted superconductor wireassembly is subjected to the thermal treatment after the Cu cover isremoved.

FIG. 24 shows an example of the third method of the production of thecoil 20 (see FIG. 6) of the composite superconducting wire 10 using thereinforcing member having a straight groove. In the method shown in FIG.24, the method is similar to the method shown in FIG. 3 except that acoiling process (step (E) in FIG. 24) is added between the wire drawingstep (step D in FIG. 24) and Cu pipe removing step (step F in FIG. 24).

In the example shown in FIG. 24, the reinforcing member 1 with theelongated superconducting material 3 is bent into a coil shape to formone or more of turn coil as shown in FIG. 6. The compositesuperconducting wire 10 shaped in the coil is subjected to the thermaltreatment after the Cu cover is removed whereby the superconductor coilhaving the desired turns can be obtained.

FIG. 25 shows an example of the fourth method of the production of thecomposite superconducting wire using the reinforcing member having astraight groove. In the method shown in FIG. 25, the method is similarto the method shown in FIG. 23 except that a twisting step (step E inFIG. 25) is added between the wire drawing step (step D in FIG. 25) andcoiling step (step F in FIG. 25).

In the example shown in FIG. 25, the drawn superconductor wire assemblyis twisted so that the groove 2 and the elongated superconductormaterial 3 is shaped in the spiral shape as shown in FIG. 4. Then thetwisted superconducting wire 10 is bent in the coiled shape. The bendsuperconductor wire assembly is subjected to the thermal treatment afterthe Cu cover is removed, whereby the coil having the desired turns withthe composite superconducting wire twisted in the spiral shape can beobtained.

In the various production methods mentioned above, it may be possible tochange the position and number of the grooves and the elongatedsuperconductor material as shown in FIGS. 1 to 20 and other than thoseshown therein. Also it is possible to select the critical temperature ofthe superconductor wire or wires as desired by selecting the material ofthe superconductor wire. Also it is possible to select the length and/orthe number of turns of the coil of the composite superconducting wire asdesired by selecting length of the reinforcing member 1. It is furtherpossible to produce the composite superconducting wire in which thesuperconductor wire coated with Al which is meltable at the time of thethermal treatment of the superconductor wire material or thesuperconductor wire coated with Ag which allows to transmit O₂ is usedand only the outer pipe is (such as Cu pipe 5) is removed.

FIG. 26 shows a further example of the method of the production of thecomposite superconducting wire. In the step A of FIG. 26, superconductorpowder 3d is preliminarily heated and sintered with a temperature higherthan 900° C. for 10 to 20 hours, so that there is obtained thepreliminarily sintered ceramic superconductor substance 3C having thestructure Y₁ Ba₂ Cu₃ O_(7-x) with the critical temperature 91° K.). Thepreliminarily sintered substance is broken in powder. The powder isaccommodated in the pipe 3b of Al and the pipe 3b with the ceramicsuperconductor powder is accommodated in the groove 2. The steps C to Eof FIG. 26 are similar to those shown in the example of FIG. 3. Afterthe reinforcing member 1 with the elongated superconductor material 3 isdrawn into an elongated wire as shown in the step F of FIG. 26, thesuperconductor wire assembly with the outer pipe 5 is subjected tothermal treatment with the temperature higher than 900° C. for severalhours.

By the method shown in FIG. 26, there can be obtained the superconductorwire in which the ceramic elongated superconductor material 3 covered byAl is accommodated in the groove 2 formed on the cylindrical surfaceportion of the reinforcing member 1 made of stainless steel or the likeand the composite superconducting wire is covered by the outer pipe 5made of Cu or stainless steel.

In the method shown in FIG. 26, since the elongated superconductormaterial 3 is already preliminarily sintered to have the desiredsuperconductor property, there is no need to supply O₂ in the step G, sothat it is possible to decrease the number of the control elements forenabling the process to be simple. In this example, the criticaltemperature of the composite superconducting wire was 91° K.

FIG. 27 shows a further example of the method of the production of thecomposite superconducting wire. In the method shown in FIG. 27, themethod is similar to the method shown in FIG. 26 except that a twistingprocess (step (G) in FIG. 27) is added between the wire drawing step(step F in FIG. 26) and the thermal treatment step (step G in FIG. 26).

In the example shown in FIG. 27, the drawn superconductor wire assemblyis twisted so that the groove 2 and the elongated superconductormaterial 3 are shaped in the spiral shape as shown in FIG. 4.

FIG. 28 shows an example of the second method of the production of thecomposite superconducting wire. In the method shown in FIG. 28, themethod is similar to the method shown in FIG. 27 except that a coilingprocess (step (G) in FIG. 28) is put in place of the twisting step (stepG in FIG. 27.

In the example shown in FIG. 28, the drawn superconductor wire assemblyis coiled so that the composite superconducting wire in the coil shapecan be obtained. The coiled superconductor wire assembly is subjected tothe thermal treatment, the coil of the composite superconducting wirehaving the desired number of turns can be obtained.

FIG. 29 shows a further example of the method of the production of thecomposite superconducting wire. In the method shown in FIG. 29, themethod is similar to the method shown in FIG. 27 except that a twistingprocess (step (G) in FIG. 29) is added between the wire drawing step(step F in FIG. 27) and the coiling step (step G in FIG. 27).

In the example shown in FIG. 29, the drawn superconductor wire assemblyis twisted so that the groove 2 and the superconductor wire 3 is shapedin the spiral shape as shown in FIG. 4 and the composite superconductingwire can be coiled.

In the various production methods shown in FIGS. 27 to 29, it may bepossible to change the position and number of the grooves and theelongated superconductor material 3 as shown in FIGS. 1 to 20 and otherthan those shown therein. Also it is possible to select the criticaltemperature of the superconductor wire or wires as desired by selectingthe material of the superconductor wire. Also it is possible to selectthe length and/or the number of turns of the coil of the compositesuperconducting wire as desired by selecting length of the reinforcingmember 1. It is further possible to prevent the oxidation of the outerpipe 5 by performing the thermal treatment by keeping the outside of theouter pipe 5 in vacuum or reductive atmosphere such as H₂ atmosphere.Moreover, in the examples shown in FIGS. 27 and 29, it is possible toperform a further wire drawing treatment after the twisting treatment.

FIG. 30 shows a still further example of the method of the production ofthe composite superconducting wire. The steps A to D in FIG. 30 aresimilar to those shown in FIG. 23. Following the wire drawing process,the elongated superconductor wire assembly is subjected to a thermalprocessing as shown the step E of FIG. 30 supplying O₂ from the end ofthe Cu pipe 5 so as to obtain the composite superconducting wire coveredwith Cu pipe 5 as shown in FIG. 31. In performing the thermal processingas shown in FIG. 30 E, the ceramic elongated superconductor material 3is shrunk to decrease the cross sectional area of the elongatedsuperconductor material 3, so that there is formed a gap between thereinforcing member 1 and the elongated superconductor material 3 andbetween the Cu pipe 5 and the elongated superconductor material 3,whereby O₂ can be sufficiently supplied to the gap and a goodsuperconductor property can be obtained.

When a bundle of twisted elongated superconductor material isaccommodated in the grove 2, and the method shown in FIG. 30 isperformed, the composite superconducting wire as shown in FIG. 32 can beobtained.

When there are formed four grooves 2 on the reinforcing member 1, andthe method shown in FIG. 30 is performed, the composite superconductingwire as shown in FIG. 33 wherein the four wires 3 are covered with theCu pipe 5 can be obtained.

In the method shown in FIG. 30, the groove 2 may be shaped in the spiralshape as shown in FIG. 34 with the outer surface of the superconductorwire assembly covered with the Cu pipe 5 which is shown in phantomlines.

FIG. 35 shows a further example of the method of the production of thecomposite superconducting wire, wherein the twisting process shown bythe step E of FIG. 35 are added in the method shown in FIG. 30.

FIG. 36 shows a further example of the method of the production of thecomposite superconducting wire, wherein the coiling process shown by thestep E of FIG. 36 is added to the method shown in FIG. 30 so as to makethe coil of the composite superconducting wire covered with the Cu pipe5.

FIG. 37 shows a further example of the method of the production of thecomposite superconducting wire, wherein the twisting process shown bythe step E and coiling step of F of FIG. 37 are added in the methodshown in FIG. 30.

In the present invention, various variations can be made. For example,the stabilizing member 4 shown in FIGS. 8 to 10 may be formed around thereinforcing member 1. When the stabilizing member is situated at thecentral portion of the reinforcing member 1, the stabilizing member 4may be made such material having a low resistance with a melting pointhigher than the sintering point of the ceramic superconductor wirematerial. In this case, as the material of the stabilizing member 4,there may be used Cu, Ag, Al and their alloy and their compositematerial. When the stabilizing member is formed around the reinforcingmember, the stabilizing member 4 may be integrally made with thereinforcing member using such material which is not reacted with theceramic superconductor wire material and has a low resistance. In thiscase, since the ceramic superconductor wire material and the stabilizingmember can be directly contacted, their contact resistance may bedecreased. Moreover, in this case, as the material of the stabilizingmember, there may be used Al covered stainless steel, Ag coveredstainless steel and Au covered stainless steel. When Al coveredstainless steel is used, by setting the sintering temperature of theceramic superconductor wire material to be higher than 900° C., sincethe Al layer is molten at the thermal treatment process of thesuperconductor wire, the ceramic superconductor wire material can befixed tightly in the groove.

As the elongated superconductor wire material to be accommodated in thegroove, there may be used such superconductor wire that thesuperconductor wire material is covered with Al layer and the Al coveredsuperconductor wire material is subjected to a thermal process with atemperature higher than 900° C. In this case, since the Al layer ismolten at the time of the thermal process and the Al is cured finally,the elongated ceramic superconductor wire material can be maintainedstabilized in the groove.

As the elongated superconductor wire material to be accommodated in thegroove, there may be used such elongated ceramic superconductor wirematerial covered by Ag layer of Cu layer. When the ceramicsuperconductor wire material is covered with Ag, O₂ can be sufficientlysupplied to the ceramic superconductor material through the Ag layer atthe time of the thermal process of the superconductor wire assembly.

When performing the thermal process in the examples shown in FIGS. 30,35, 36 and 37, in place of supplying O₂, the substance C defined in theequation (1) may be supplied from the end of the outer pipe 5.

What is claimed is:
 1. A composite superconducting wire which comprisesan elongated reinforcing member, at least one groove defined on thesurface portion of the reinforcing member so as to extend generally in alongitudinal direction, and ceramic superconductor material accommodatedin and extending along said groove, the ceramic superconductor materialhaving a width less than the width of the groove, the groove being open.2. The composite superconducting wire according to claim 1, wherein saidreinforcing member is formed in a spiral shape.
 3. The compositesuperconducting wire according to claim 1, wherein said groove is formedin a spiral shape.
 4. The composite superconducting wire according toclaim 1, wherein a plurality of grooves are defined on the surfaceportion of the reinforcing member.
 5. The composite superconducting wireaccording to claim 1, wherein the ceramic superconductor material isformed of a material defined by the following equation:

    Aa Bb Cc

wherein A denotes at least one element selected from the IA group, IIAgroup, and IIIB group of th periodic table, B denotes at least oneelement selected from the IB group, IIB group and IIIA group of theperiodic table, and C denotes at least one element selected from thegroup consisting of oxygen, fluorine, nitrogen, carbon and sulfur. 6.The composite superconducting wire according to claim 1, wherein thereinforcing member is made of a material which does not react duringthermal processing of the ceramic superconductor material and has athermal resistivity against the thermal processing temperature.
 7. Acomposite superconductor wire according to claim 5, wherein the ceramicsuperconductor material is made of the elements Y, Ba, Cu and O.
 8. Thecomposite superconducting wire according to claim 1, wherein saidsuperconductor material is covered by Al.
 9. The compositesuperconductor wire according to claim 1, wherein said superconductormaterial is covered by Ag.
 10. The composite superconducting wireaccording to claim 1, wherein said superconductor material is covered byCu.
 11. The composite superconducting wire according to claim 1, whereinsaid superconductor material is made of twisted ceramic superconductorsfilaments.
 12. A composite superconducting wire which comprises anelongated reinforcing member, at least one open groove defined on thesurface portion of the reinforcing member so as to extend generally in alongitudinal direction, a ceramic superconductor material accommodatedin and extending along said groove, the ceramic superconductor materialhaving a width less than that of the groove, and a stabilizing membercontained in the reinforcing member, extending in the longitudinaldirection of the reinforcing member.
 13. The composite superconductingwire according to claim 12, wherein said stabilizing member is providedat a central portion of the reinforcing member.
 14. The compositesuperconducting wire according to claim 12, wherein said stabilizingmember is made of Cu, Ag and/or Al and their alloy or their compositematerial.
 15. The composite superconducting wire according to claim 12,wherein said stabilizing member is formed on the outer peripheralsurface of the reinforcing member.
 16. A composite superconducting wirewhich comprises an elongated reinforcing member, at least one opengroove defined on the surface portion of the reinforcing member so as toextend generally in a longitudinal direction, a ceramic superconductormaterial accommodated in and extending along said groove, the ceramicsuperconductor material having a width less than that of the groove, andan outer enclosure for enclosing said reinforcing member with theceramic superconductor wire so as to provide a path to allow flow ofcooling medium around the reinforcing member.
 17. The compositesuperconducting wire according to claim 16, wherein the ceramicsuperconductor material is formed of a material defined by the followingequation:

    Aa Bb Cc

wherein A denotes at least one element selected from the IA group, IIAgroup, and IIIB group of the periodic table, B denotes at least oneelement selected from the IB group, IIB group and IIIA group of theperiodic table, and C denotes at least one element selected from thegroup consisting of oxygen, fluorine, nitrogen, carbon and sulfur. 18.The composite superconducting wire according to claim 16, wherein saidwire is formed in a spiral shape.
 19. The composite superconducting wireaccording to claim 18, wherein said groove is formed in a spiral shape.20. The composite superconducting wire according to claim 16, wherein aplurality of grooves are defined on the surface portion of thereinforcing member.
 21. The composite superconducting wire according toclaim 16, wherein said reinforcing member is made of a material whichdoes not react during thermal processing of the ceramic superconductormaterial and has a thermal resistivity against the thermal processingtemperature.